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Surface formation in electrical discharge machining (EDM) involves melting, evaporation, re-solidification and crater overlapping. However, almost all existing models concerning surface formation in EDM only consider the thermal process and ignore hydrodynamic phenomena during machining. Herein, a novel three-dimensional thermo-hydraulic coupling model incorporating the arbitrary Lagrangian–Eulerian scheme was developed to address the above problem. The model comprehensively considered the surface deformation caused by melt flow, temperature-dependent material properties, phase changes and the effects of practical forces on melt pools to simulate surface formation on an anodic workpiece at a discharge current of 2 A. Simulation results demonstrate that during single-pulse discharge, molten material flowed radially to the crater periphery. The radial melt flow was driven by evaporation recoil pressure and thermocapillary force. The effect of evaporation recoil pressure on melt flow was gradually counteracted by that of surface tension after discharge ignition, and thermocapillary force became the dominant factor that maintained the existence of bulges around craters. During multiple discharges, the bulges generated by different discharges underwent superposition owing to the flow of molten material and subsequently formed surface peaks. The simulation results also provide the measurements of crater diameter, surface roughness and recast layer thickness, which are consistent with experimental results. The proposed modelling method can provide a useful reference for further investigations on surface integrity in EDM with minimal computing resource requirements. • A novel 3D thermo-hydraulic coupling surface formation model for EDM was proposed. • The effects of evaporation recoil pressure and thermocapillary force on melt pool dynamics in EDM were investigated. • Simulation results of multiple discharges show good consistency with experiment results concerning surface properties. [ABSTRACT FROM AUTHOR]

Electrical discharge machining (EDM) method is an innovative method for the fabrication of structured array surfaces on binderless tungsten carbide (WC) which is a typical embossing mold material, compared to traditional machining methods. To improve the convenience of electrode replacement and the fabrication efficiency of the structured array, a novel self‐assembly ball electrode is innovatively developed. The feasibility of machining binderless WC with a self‐assembly ball electrode was studied and its effect on profile deviation analyzed. Furthermore, the discharge condition's effect on surface roughness, material removal rate (MRR), and tool wear ratio (TWR) was investigated. The microstructure, phase structure, and element distribution of binderless WC caused by EDM were characterized by Raman spectroscopy, scanning electron microscopy, and energy dispersive x‐ray spectroscopy. The results indicated that the maximum profile deviation of the different random structured arrays was about 3.7 μm. The surface roughness of all structured arrays was below 1 μm. The maximum TWR was about 0.008 mm3/min. Besides, the binderless WC surface after EDM presented strong D and G carbon peaks, which means the precipitation and transformation of the WC phase during the discharge process. Finally, different kinds of self‐assembly ball electrodes are developed and used to fabricate the lens array structures on binderless WC. The fast fabrication of the micro‐lens array surfaces in different arrangements sheds some light on the design and manufacturing of other functional structured surfaces. [ABSTRACT FROM AUTHOR]

Electrical discharge machining is a versatile machining technology that uses precisely directed sparks within the range of the dielectric fluid and between the electrodes to make electrically conductive products. The influence of different processing parameters on diverse metal matrix composites, including new reinforcing elements (silicon carbides, aluminium oxides and nitrides), and the modifications that occur as a consequence of each of these components are discussed in this article. As a result, new reinforcing materials and ways for optimising performance have emerged. The goal of this study is to provide analysts with research data that will allow them to effectively use EDM principles and, more particularly, to investigate process characteristics in order to enhance the process of advanced PMEDM operation. [ABSTRACT FROM AUTHOR]

This work aims to optimize the machining parameters and study the effect of powder-mixed dielectric fluid on the electrical discharge machining (EDM) process. The TOPSIS method of optimization is adopted to identify the optimal machining parameters. HCHCr die steel is preferred as a machining material. Due to their hard and ductile nature, Ni, Zr, and Ni+Zr were selected as powder inclusion in dielectric fluid. An L9 array Taguchi DOE is preferred to perform the experiments with parameters like peak off time, pulse off time, and pulse current. TOPSIS study revealed that the third level of powder dielectric fluid (Ni+Zr), 7A peak current, 9 µs pulse on time, and 2 µs pulse off time were specified as the optimal condition. Pulse on time (Ton) significantly impacted metal removal rate and surface roughness while machining operation on HCHCr die steel. SEM analysis was done to find the effect of powder-mixed dielectric fluid, while EDAX analysis was done to ensure the presence of powder inclusion. [ABSTRACT FROM AUTHOR]

Multiwall carbon nanotube buttressed aluminium 7075 metal matrix composite was synthesized through an amended liquid metallurgy method, which consisted semisolid stirring, ultrasonic treatment and squeeze casting. Aim was to investigate its machinability and surface morphology during electrical discharge machining. Variable machining factors were peak current, pulse‐on time and gap voltage, whereas the responses under investigation were electrode wear rate, material removal rate and average surface roughness. Results revealed electrode wear rate, material wear rate and average surface roughness increased on increasing peak current and pulse‐on time, but all these responses behaved inversely with the increase of gap voltage. Average surface roughness reduced by around 44 % on reducing the peak current from 10 A to 4 A and increasing gap voltage from 55 V to 80 V at constant pulse‐on time of 300 μs; however, it increased by around 25 % on reducing the gap voltage from 80 V to 55 V and increasing the pulse‐on time from 100 μs to 300 μs at constant peak current of 10 A. Significance of the process parameters were verified, regression models were developed and morphology of the machined surfaces was studied. Finally, multiple response optimization was conducted following grey relational approach. [ABSTRACT FROM AUTHOR]

The study was performed to determine the optimum flushing condition for electrical discharge machining (EDM) of functional material titanium VT6 obtained by plasma cladding with a thermal cycle. Copper is used as an electrode tool (ET) to machine functional materials. The optimum flushing flows are analyzed theoretically by using ANSYS CFX 20.1 software which is also validated by an experimental study. It was observed that while machining the functional materials to adepth of 10 mm or more, the turbulence fluid flow dominates when nozzle angles are 45° and 75°, consequently drastically affecting the quality of flushing and the performance of the EDM. For the highest machining performance, the nozzles should be at an angle of 15° relative to the tool axis. The optimum flushing at deep hole EDM process minimizes the occurrence of debris deposition on tool electrodes, thus facilitating stable machining of functional materials. The adequacy of the obtained models was confirmed experimentally. It has been established that EDM of a hole with a depth of 15 mm, an intense accumulation of sludge, is observed in the processing zone. There arebuild-ups exceeding 3 mm in cross-section after EDM. This build-up leads to a short circuit and a reduction in surface quality and productivity. It has been proven that not correct flushing leads to intensive wear of the tool and a change in its geometric shape and, accordingly, to a decrease in the quality of EDM. [ABSTRACT FROM AUTHOR]

Electrical discharge machining (EDM) is widely applied for machining difficult-to-cut materials in mold and die industries. However, the major limitations associated with the EDM are low productivity and poor surface integrity of the machined surfaces. In recent years, several developments have been applied to overcome such limitations of EDM. Electrical discharge grinding (EDG) is a hybrid machining process that simultaneously involves the spark erosion action of EDM and the mechanical abrasion action of the grinding wheel for the material removal purpose. The rotating motion of the grinding wheel also contributes to the easy removal of debris particles, thereby improving the material removal. It is evident from the literature that the rotating motion of the grinding wheel enhances the flushing mechanism resulting in better performance of the process. This paper aims to present a comprehensive review of the research carried out in EDG, highlighting the result of the experimental, modeling, and optimization techniques applied in this area. Initially, the background of EDM and the need for hybrid EDM processes have been presented. Then, a few hybrid EDM processes have been discussed, addressing their advantages and limitations. Further, the concept of EDG and electrical discharge diamond grinding (EDDG) has been discussed, along with the classification of the EDDG process. Finally, this paper explores the current research status and future research perspective in the area of EDG and EDDG processes. [ABSTRACT FROM AUTHOR]

Amorphous alloys are a new type of multi-functional advanced material with the properties of general metal materials and glass, which are also called metallic glasses. They have good comprehensive properties, such as a wide application range, low cost, and high reusability. Using reasonable process parameters, non-traditional machining can not only realize the machining of complex amorphous parts, but also avoid the crystallization and oxidation of amorphous alloys, realizing tasks that cannot be accomplished by traditional machining. Therefore, this review systematically summarizes the research status and development potential of amorphous alloys fabricated using non-traditional machining methods. First, we introduce the principles of laser machining, ultrasonic machining, electrical discharge machining, electrochemical machining, and other non-traditional machining methods for amorphous alloys. Subsequently, the influence of the machining parameters and other external conditions on the machining effect is summarized. The machining cost, machining efficiency, and environmental impact of these non-traditional machining methods were compared. Finally, non-traditional machining technology for amorphous alloys is summarized and discussed. • The processing principles of non-traditional machining methods are summarized. • The influences of processing parameters on the machining effect are reviewed. • Costs, effects, and pollution of non-traditional machining are compared. • The limitations or shortages of non-traditional machining methods are summarized. [ABSTRACT FROM AUTHOR]

Electrical discharge machining (EDM) is a nonconventional machining process that involves the formation of a plasma in an interelectrode gap filled with a dielectric that melts and vaporizes the electrodes (tool and workpiece) when a voltage is applied across them. This work models the plasma discharge in the EDM process to describe plasma characteristics such as electron density, heavy species densities, plasma potential, and plasma temperature using chemical kinetics, fluid flow, and heat transfer mechanisms in a 1D domain in the direction of the gap. The 1D domain allows the model to utilize surface reactions on the electrode walls necessary for sustaining the plasma reactions. The domain also provides a perspective of the plasma characteristics near the workpiece. Temperature results are compared with the experimental data obtained from spectrometer measurements. Additionally, an estimate of the plasma diameter is made and compared with actual high-speed camera images. The effect of EDM parameters such as supply voltage and interelectrode gap size on plasma characteristics is studied. The model predicts the incumbent heat flux on the workpiece electrode for small gaps which could have applications in the development of melt-pool models of EDM. Finally, the model provides a physics-based understanding of the mechanisms of plasma generation in the EDM process. [ABSTRACT FROM AUTHOR]

Electrical discharge machining (EDM) is a nonconventional machining process that involves the formation of a plasma in an interelectrode gap filled with a dielectric that melts and vaporizes the electrodes (tool and workpiece) when a voltage is applied across them. This work models the plasma discharge in the EDM process to describe plasma characteristics such as electron density, heavy species densities, plasma potential, and plasma temperature using chemical kinetics, fluid flow, and heat transfer mechanisms in a 1D domain in the direction of the gap. The 1D domain allows the model to utilize surface reactions on the electrode walls necessary for sustaining the plasma reactions. The domain also provides a perspective of the plasma characteristics near the workpiece. Temperature results are compared with the experimental data obtained from spectrometer measurements. Additionally, an estimate of the plasma diameter is made and compared with actual high-speed camera images. The effect of EDM parameters such as supply voltage and interelectrode gap size on plasma characteristics is studied. The model predicts the incumbent heat flux on the workpiece electrode for small gaps which could have applications in the development of melt-pool models of EDM. Finally, the model provides a physics-based understanding of the mechanisms of plasma generation in the EDM process. [ABSTRACT FROM AUTHOR]

Electrical discharge machining (EDM) is a nonconventional machining process that involves the formation of a plasma in an interelectrode gap filled with a dielectric that melts and vaporizes the electrodes (tool and workpiece) when a voltage is applied across them. This work models the plasma discharge in the EDM process to describe plasma characteristics such as electron density, heavy species densities, plasma potential, and plasma temperature using chemical kinetics, fluid flow, and heat transfer mechanisms in a 1D domain in the direction of the gap. The 1D domain allows the model to utilize surface reactions on the electrode walls necessary for sustaining the plasma reactions. The domain also provides a perspective of the plasma characteristics near the workpiece. Temperature results are compared with the experimental data obtained from spectrometer measurements. Additionally, an estimate of the plasma diameter is made and compared with actual high-speed camera images. The effect of EDM parameters such as supply voltage and interelectrode gap size on plasma characteristics is studied. The model predicts the incumbent heat flux on the workpiece electrode for small gaps which could have applications in the development of melt-pool models of EDM. Finally, the model provides a physics-based understanding of the mechanisms of plasma generation in the EDM process. [ABSTRACT FROM AUTHOR]

Electrical discharge machining (EDM) is a well-known manufacturing process that is reported for several times as an effective technique for cutting of nickel-based superalloy of Inconel 718 (IN718). A majority of existing researches in EDM of Inconel 718 are focused on machinability of material considering production rate, tool wear, surface roughness and dimensional tolerances. To the best of author's knowledge, corrosion resistance EDMed Inconel 718 has hardly been taken into consideration. In the present work, an experimental study was made to understand how the electrical discharge machining parameters, viz. pulse current, pulse on time and rotational motion of the tool electrode, influence the corrosion properties of IN718. Technique of potentiodynamic polarization curve was utilized to measure IC and EC of the samples. A number of seven samples were machined using single-factor experiments design, and the effect of EDM parameters on foresaid corrosion indices was studied. Surface roughness, surface morphology, hardness and residual stress distributions were taken into account for justification of the variations. It was obtained from the results that as a result of increase in current from 5 to 15A, the corrosion rate increases, where the current density increases from 0.15 to 0.28 μA/cm2, and corrosion potential decreases from 0.51 to − 2.49 VSCE. In addition, it was found that less value of pulse on time, i.e., 600 μs, results in best corrosion properties where increase up to 800 μs results in increase in corrosion density from 0.11 to 0.19 μA/cm2 and also reduction of corrosion potential from −0.34 to −1.13 VSCE. It was further found that increase in tool rotational speed from stationary condition up to 200RPM results in enhancement of corrosion resistance; here, the current density reduces from 0.4 to 0.088 μA/cm2 and increase in corrosion potential from − 1.89 to 0.11 VSCE. [ABSTRACT FROM AUTHOR]

Modern industry is focused on looking for new and effective technologies to manufacture complex shapes from alloys based on nickel and chromium. One of the materials widely used in the chemical and aerospace industry is Hastelloy C-22. This material is difficult to machine by conventional methods, and in many cases, unconventional methods are used to manufacture it, such as electrical discharge machining (EDM). In the EDM process, the material is removed by electrical discharges between a workpiece and a tool electrode. The physical and mechanical properties of the tool electrodes have a direct impact on the process efficiency, machining accuracy, and surface roughness. Currently, there has been a significant increase in the use of graphite as a material for tool electrodes due to the low purchase cost of the raw material, good machinability, and high sublimation temperature. In this work, an experimental investigation of the influence of the grain size of the graphite tool electrode on material removal rate (MRR), tool wear rate (TWR), and surface roughness (Ra) of Hastelloy C-22 was carried out. Two POCO graphite tool electrodes with a grain size of 1 µm (AF-5) and 10 µm (S-180) were used. Based on the experimental studies, empirical models describing the influence of machining parameters on technological indicators and the condition of the surface texture were determined. The research indicates that graphite with a larger grain provides higher process efficiency with high relative wear of the tool electrode. The lowest surface roughness was obtained for graphite with a smaller grain size (AF-5). The analysis of the machining parameters proves that the discharge current and pulse duration are the main factors determining the MRR and Ra values for both AF-5 and S-180 graphite. The time interval is the dominant parameter with regard to the relative wear of the graphite electrode. [ABSTRACT FROM AUTHOR]

Sinking electrical discharge machining (EDM) is a vital machining technology used in modern mechanical manufacturing. However, the conventional sinking EDM, which utilizes an oil-based working medium, presents disadvantages such as low machining efficiency, harmful gas emissions, and fire hazards. Although researchers have attempted to use pure water as the working medium, pure water cannot replace oil and has not yet been industrially applied as a working medium because of its low machining efficiency and thick surface recast layer. Herein, we propose sustainable and green sinking EDM utilizing foam water (SEDM-FW) as the working medium, a method that uses pressurized foam water, ultrastrong energy discharge, and upward electrode feeding. The proposed method is cost effective, and its machining efficiency is more than three times higher than that of the conventional sinking EDM at the same peak current. The use of foam water instead of oil as the working medium solves environmental pollution problems associated with the conventional sinking EDM. In terms of environmental performance, the SEDM-FW produces gas byproducts that do not contain any harmful components, including 1,3-butadiene and benzene, which are present in the conventional sinking EDM. Compared with using pure water, using foam water as the working medium in conjunction with an appropriate gas-to-liquid ratio can double the machining efficiency, reduce the thickness of the recast layer by more than half, and reduce the size of surface microcracks. Using gas-dominated foam water, surface microcracks can be eliminated, and a zero-thickness recast layer can be achieved. [Display omitted] • A sustainable and green sinking EDM method (SEDM-FW) is proposed. • Foam water is used as the working medium, which replaces conventional oil and pure water. • Gas byproducts of SEDM-FW are completely harmless to humans and environment. • A proper gas-to-liquid ratio has higher MRR, lower REWR, and good surface integrity. • Gas-dominated foam water can eliminate microcracks and achieve zero-thickness recast layers. [ABSTRACT FROM AUTHOR]

The discharge current waveform affects the processing characteristics and surface integrity by affecting the process of energy input. At present, although the rectangular current waveform is widely used in electrical discharge machining (EDM), there is not enough evidence to prove that it is the most suitable. Therefore, in this study, the influence of the discharge current waveforms on processing characteristics and surface integrity was investigated and compared under similar pulse energy. Three types of discharge current waveforms including rectangular (Rec), triangular (Tri), and trapezoidal (Tra) are used for processing. The material removal amount, surface topography, roughness, phase compositions, white layer thickness, and residual stress were investigated and analyzed. The results showed that Tri could remove the most materials per pulse-on duration, followed by Tra. Compared with Rec, the size of craters and debris on the sample surface produced by the Tri and Tra was larger. The surface roughness and residual stress of samples processed by Tri were the highest. When the discharge current waveform was constant, XRD spectra of samples fabricated by EDM under different pulse energy were almost the same. Compared with Rec, the diffraction peaks of samples produced by Tri and Tra were reduced. When the pulse energy was low, the white layer of samples processed by Rec was thinner than that processed by Tri. This phenomenon was reversed when the pulse energy was high. The white layer thickness of the sample fabricated by Tra was between the samples processed by Rec and Tri regardless of pulse energy. [ABSTRACT FROM AUTHOR]

Electrical discharge machining (EDM) is very essential unconventional electrothermal machining process to machine the contour profile of hard materials in modern production industries. The liquid dielectric fluid has been replaced by the gas and minimum quantity of liquid mixed with gas (gas mist) to encourage the green machining processes. The various gases and gas mist have been used as the working fluid in dry and near-dry EDM, respectively. The research-contextual, various dielectric fluids, sustainable and innovative developments, process parameters, machining characteristics, and optimization techniques applied in various dry and near-dry EDM have been illustrated through an extensive literature survey. Future research opportunities in both dry and near-dry EDM have been summarized to promote eco-friendly EDM research activities. [ABSTRACT FROM AUTHOR]

Highly dense electrically conductive silicon carbide (SiC)–(0, 10, 20, and 30 vol%) titanium boride (TiB2) composites with 10 vol% of Y2O3–AlN additives were fabricated at a relatively low temperature of 1800°C by spark plasma sintering in nitrogen atmosphere. Phase analysis of sintered composites reveals suppressed β→α phase transformation due to low sintering temperature, nitride additives, and nitrogen sintering atmosphere. With increase in TiB2 content, hardness increased from 20.6 to 23.7 GPa and fracture toughness increased from 3.6 to 5.5 MPa m1/2. The electrical conductivity increased to a remarkable 2.72 × 103 (Ω cm)–1 for SiC–30 vol% TiB2 composites due to large amount of conductive reinforcement, additive composition, and sintering in nitrogen atmosphere. The successful electrical discharge machining illustrates potential of the sintered SiC–TiB2 composites toward extending the application regime of conventional SiC‐based ceramics. [ABSTRACT FROM AUTHOR]

In electrical discharge machining (EDM), the discharge current waveform that determines the process of energy input has an important influence on machining characteristics as the discharge voltage is constant after the dielectric is broken down. In the past, the influence of pulse-on time and current on the surface metamorphic layer under rectangular current waveform has been reported, while the influence of non-rectangular current waveform on the surface metamorphic layer is still elusive. In this study, the difference in the surface metamorphic layer of the workpiece processed by triangular current waveform and rectangular current waveform under the same pulse energy was investigated and analyzed. Compared with rectangular current waveform, surface roughness of the workpiece processed by triangular current waveform was higher. Cracks on the surface of the sample produced by rectangular current waveform always exist from 0.088 to 1.96 mJ. However, it was difficult to observe cracks on the surface of the sample processed by the triangular current waveform when the pulse energy was higher than 0.41 mJ. There is no obvious difference in the intensities of diffraction peaks α-Fe, γ-Fe, and cementite for the samples processed by rectangular current waveform with different discharge energy. However, for the workpiece fabricated by triangular current waveform, the peaks of cementite and γ-Fe increased as the pulse energy increased. When the pulse energy was low, the white layer of the sample processed by rectangular current waveform was thinner than that processed by triangular current waveform. This phenomenon is reversed when the pulse energy is high. [ABSTRACT FROM AUTHOR]

The influences of electrical and non-electrical parameters on surface integrity during the EDM process have been widely researched in past years. However, the effect of the energy input process at the same discharge energy is seldom reported. To select more suitable processing parameters according to the processing requirements, we have studied the influence of the energy input process on processing characteristics and surface properties. Two different energy input modes (high discharge current with short pule-on time (HIST) and low discharge current with long pule-on time (LILT)) are used. When the discharge energy is the same, the HIST mode has a higher material removal amount, while the sample produced by the LILT mode presents a lower surface roughness and residual stress. More surface cracks are detected on the samples processed by the LILT mode, and their dimensions in terms of length and width are greater than that of the HIST mode. The microstructure of the EDM surface is composed of α-Fe, γ-Fe, and cementite. When the discharge energy is higher than 0.24 mJ, the intensities of diffraction peaks γ-Fe and cementite on the EDM workpiece surface produced by the HIST mode are higher. The white layer thickness is related to the discharge energy and its input process. When the discharge energy is lower than 0.51 mJ, the white layer is thinner under the LILT mode. However, the white layer of the EDM sample fabricated by the HIST mode is thinner when the discharge energy is higher than 0.51 mJ. [ABSTRACT FROM AUTHOR]

Boron carbide (B 4 C) composites containing 0–10 wt.% graphene nanoplatelets (GNPs) were consolidated using hot pressing at 1950 °C for 60 min under 30 MPa in an argon atmosphere. Their electrical discharge machining (EDM) characteristics were evaluated for the first time. Additionally, the effects of GNPs on the microstructure, electrical conductivity, material removal rate (MRR), and surface roughness (R a) of B 4 C composites were investigated. The results show that the B 4 C composite containing 10 wt.% GNPs exhibited the highest electrical conductivity of 4997 S·m−1 because of the formation of GNPs conductive networks. Under a fine machining condition, the MRR of the B 4 C composite was enhanced by 43.5 % (from 6.55 to 9.40 mm3 min−1) compared with that of monolithic B 4 C. Furthermore, the R a decreased to 1.12 μm, which was significantly lower than that of pure B 4 C (2.44 μm). Scanning electron microscope and energy disperse spectroscopy analysis of the EDM surfaces were used to determine that the main material removal mechanisms for B 4 C composites with less than 2 wt.% GNPs were spalling and melting. As the GNPs content increased, B 4 C grain fallout, melting, and evaporation became more dominant. The other mechanisms, including thermal shock and oxidation, are also discussed in detail. [ABSTRACT FROM AUTHOR]

Electrical discharge machining (EDM) is an unconventional machining process based on removing material by successive electrical discharges. The tool electrode wear must be kept as minimal as possible to produce high-precision components. This scope proposes the development of a new technique for identifying wear on electrodes and its evolution using acoustic emission (AE) signals. Therefore, EDM tests were performed on AISI H13 steel parts with electrolytic copper tool electrodes under different conditions with concomitant AE signal measurements. In these tests, the first one has the following parameters: voltage pulse duration time (te) of 150 μs; the time interval between two successive voltage pulses (to) of 14.84 μs; electrical current of 33 A; and positive polarity electrode. For the second test: duration of the voltage pulse of 2 μs; the time interval between two successive voltage pulses of 4.90 μs; electrical current of 18 A; and negative polarity electrode. In this way, a wear rate 28.3 times higher was obtained in the electrolytic copper electrode in the first test, more aggressive due to its parameters, for the same machining time compared to the second test. Finally, the wear of the tool electrodes was related to the AE signals from machining; initially in this study, the workpiece's mass loss was not verified. These signals were analyzed using the short-time Fourier transform techniques and spectral entropy. The results showed that the signals using the new technique of relation respond to wear and are sensitive to the electrode's wear rate. [ABSTRACT FROM AUTHOR]

Electrical discharge machining (EDM) is the unconventional machining technique used extensively for machining difficult-to-machine materials with lower material removal rate and poor surface roughness. To overcome these drawbacks, synthetic dielectric fluid is replaced with nanoparticle-infused biodegradable dielectric fluid in the machining of Hastelloy material. This paper focusses on the machining performances of Hastelloy in EDM using various concentrations of 0.5, 1 and 1.5 wt% of nano-zirconia dispersed in biodegradable canola oil methyl ester as the dielectric medium, and these characteristics were compared with those of the synthetic dielectric medium. Based on the D-optimal design coupled with cuckoo search algorithm, machining was carried out with various dielectric fluids and their influences on the metal removal rate, surface roughness, surface morphology and surface topography in EDM studied. The results proved that the canola oil methyl ester containing 0.5 wt% of nano-zirconia (C-0.5) had provided good surface finish, better surface topography, smooth surface morphology and high metal removal rate in comparison with the other dielectric fluids used in this study. [ABSTRACT FROM AUTHOR]

The efficient removal of material debris by flushing is critical for the performance and the surface quality of the electrical discharge machining (EDM) manufacturing process. The particle concentration alters the thermal, mechanical, and electrical properties of the particle–dielectricum suspension and affects the manufacturing process and the surface quality by inducing high thermal loads. For the first time, we perform a direct particle–fluid simulation of the flushing cycle in a generic EDM cavity using a hierarchical Cartesian sharp-interface cut-cell method. The flow around each debris particle is completely resolved and the heat transfer between the particles and the fluid is taken into account. The rate of material removal and the cooling performance of the flushing mechanism are studied for three-volume loadings. The results show that the flow around the particles has a pronounced impact on the heat transfer between the dielectricum and the workpiece. A particle loading of 14% increases the mean heat transfer by approximately 16%. The particle loading also has a pronounced impact on the rate at which particles are flushed out of the cavity. Increasing the initial volume loading from 6% to 14% decreases the amount of particles that get flushed out of the cavity by 14%. [ABSTRACT FROM AUTHOR]

To meet the increasing demand for wire electrical discharge machining (WEDM) under extreme conditions such as ultra-high thickness cutting, micro-wire cutting, micro-energy finishing, and ceramic composites machining, a concept of multichannel discharge WEDM under semiconductor characteristics was proposed. The essence of this conception is that under these extreme machining conditions, the electrode wire or workpiece — or even both of the two electrodes — cannot be treated as electrically conductive materials of the conventional WEDM due to their high electrical resistance. However, they can exhibit electrical discharge behavior like semiconductors, which is defined as semiconductor characteristics. The conventional WEDM theory and related technologies cannot be applied to extreme WEDM because conventional WEDM only has one discharge channel per pulse, whereas multiple discharge channels can be generated by each pulse in extreme WEDM. Therefore, a suitable theory needs to be developed for extreme WEDM under semiconductor characteristics. Based on the multichannel discharge behavior of semiconductors, experiments were conducted on high-efficiency machining with multichannel discharge by stacking several workpieces as an assembly with semiconductor characteristics. It was proved that the multichannel discharge WEDM is capable of achieving high machining efficiency, as well as enhanced surface quality and lower wear of electrode wire. The proposed multichannel discharge WEDM sets up the foundation for the establishment of the theoretical system of EDM under semiconductor characteristics. [ABSTRACT FROM AUTHOR]

In this work, the effect of the presence and the diffusion of the Copper from the tool electrode onto the EDMed stainless steel (SS) surface have been investigated by electrochemical impedance spectroscopy (EIS), X-ray diffraction (XRD), Quantometer analysis, and Optical microscopic observations. The Taguchi method was used to study the effects of Pulseon time (ton), Pulse-off time (toff), discharge current (I), and overall machining time (τ) on chemical composition, microstructures, micro-cracks, and electrochemical corrosion of EDMed stainless steel workpieces. The results show that the variation of machining parameters changes the chemical composition of the workpieces. By increasing the discharge current and decreasing the Pulse-on time, the copper and the carbon diffuse onto the surface of the workpiece. Consequently, the chemical composition of the workpiece surface changes, leading to an increment of the corrosion resistance. The XRD analysis shows the formation of Fe2C, Cr3C2, and CuNi. In addition, at higher values of discharge current and ton/toff ratio, the micro-cracks propagate on the surface of the workpiece. [ABSTRACT FROM AUTHOR]

The influence of electrical discharge machining (EDM) on thermal barrier coating (TBC) in a two-step drilling of nickel-based superalloy has been studied. The TBC was coated on the superalloy using electron beam physical vapor deposition (EB-PVD). Simulation result shows that the temperature at TBC/metal interface increases with pulse-on time and peak current. The temperature will exceed the melting point of the coating material when using relatively large pulse energy. Experimental result reveals that large pulse-on time or high peak current caused defect such as cracking at coating sidewall and delamination at the TBC/metal interface. For EDM drilling holes with inclined angle, the leading edge had worse condition of debris evacuation, and consequently caused secondary discharge which resulted in melt and spalling of the coating material. In addition, relatively larger pulse-on time and greater peak current might result in greater thermal stress gradient at the interface and subsequently lead to cracking or spalling at the coating layer. Therefore, process conditions of short pulse-on time, longer pulse-off time, and small peak current are recommended for EDM drilling of the EB-PVD coated nickel-based superalloy. [ABSTRACT FROM AUTHOR]

Closed curved and twisted channels are widely used in key parts of aerospace vehicles; however, they are difficult to process. Electrical discharge machining is a common method for machining curved and twisted channels of integral components. The electrode trajectory determines the machining quality and efficiency. We adopted a target evaluation function to distinguish between the local and global optima for an integral component with a long and narrow two-dimensional curved and twisted channel. In addition, we combined heuristic search and rapidly exploring random tree search to design and optimize the machining trajectory of the electrode. Finally, we conducted a comparative experiment between a preliminary design scheme and the proposed optimization method. The test results show that the machining efficiency and accuracy of the proposed method are higher than those of the preliminary design scheme. Furthermore, the machining trajectory generated by the proposed method satisfies the comprehensive requirements to produce two-dimensional curved and twisted channels. [ABSTRACT FROM AUTHOR]

[Display omitted] • Deterministic cellular lattice structures of IN718 are fabricated through LPBF. • Through-holes EDM drilling is performed on LPBF-fabricated lattice structures. • Machined holes show dimensional variability due to pores, nodes, and lattice defects. • Near-circular through-holes machined by optimizing EDM parameters and electrode positioning. Additive manufactured (AM) metallic lattice structures are being largely explored for different engineering applications. The fastening, implantation, and installation of such lattice structures demand secondary processing. In the current work, through-hole drilling is performed using electrical discharge machining (EDM) on Inconel 718 (IN718) lattice structures fabricated by laser powder bed fusion (LPBF). The challenges in EDM hole drilling have been encountered and uncertainty in the machined holes owing to periodically open pores and nodes in the lattice structures sizes has been identified. Finally, an experimental strategy has been proposed for near-circular hole drilling by design optimization and tool positioning with respect to the cellular structures. [ABSTRACT FROM AUTHOR]

Electrical discharge machining (EDM) is one of the most explored nonconventional machining processes due to its ability to machine intricate shapes on conductive materials. However, tool wear is one of the major challenges in the EDM process as it directly affects the accuracy of machining, surface roughness, reproduction of geometrical characteristics on the workpiece and cost of the process. Lots of work have been done to minimize the tool wear by improving the discharge conditions by controlling the EDM process parameters, varying the dielectric characteristics, powder-mixed dielectric methods and ultrasonic-assisted methods. However, minimizing the tool wear by the above approaches also constrains the material removal rate from the workpiece and accuracy of the process. This review highlights the efforts done by the researchers to improve tool wear by recently developed techniques or modifications. Researches available in the field of using treated tool electrode, cooled tool electrode, coated tool electrode, noble tool materials and other techniques are highlighted. [ABSTRACT FROM AUTHOR]

The demand for higher efficiency in aircraft propulsion engines leads to materials with increasing thermomechanical strengths and new designs inducing filigree geometries of blisks and disks. Because of new designs which induce tighter tolerances, the high mechanical process forces in conventional cutting processes like broaching cause inacceptable geometrical deviations and high tooling costs. Due to the electro-thermal material removal mechanism, electrical discharge machining (EDM) ensures a force free and thus precise machining. The manufacture of fir tree slots in nickel-based alloys by wire EDM has been investigated in the last few years and the process was verified as an alternative technology for broaching. To get a better competitive position, the productivity can be prospectively increased by using an additional indexing rotary axis which ensures a precise and automated production of rotationally symmetric components and reduce production times, e.g., for the manufacture of fir tree slots on a disk. Nevertheless, the application of these axes cause changed flushing conditions and can also affect the electrical contacting as well. Both influence the process performance and demand a technology development or adjustment of standard machining technologies. The influence of these changed machining conditions has not been investigated scientifically to date. In this paper, the surface integrity and process performance of fir tree slots machined by wire EDM on the machine table are compared with the manufacture by using an additional indexing rotary axis. [ABSTRACT FROM AUTHOR]

This study fabricates a roughing electrode of electrical discharge machining (EDM) using a rapid prototyping (RP) system and investment casting technology, which reduces the overall time that is required for fabrication and the cost of the manufacturing process for a selected electrode. Pro/E (3D CAD) software is used to design the electrode prototype, which has a complex appearance, and to transform the CAD model into stereolithography (STL) format. An RP machine (Zcorp 402 3DP) is used to construct a gypsum-based powder model. After a sealing process using the permeation of resin, the water resistance and strength of the gypsum-based material are increased. The manufacturing process then involves creating a wax model with a gypsum electrode that is strengthened by resin permeation by casting a vulcanized silicone molding. The brass electrode is fabricated using investment casting technology. The results of an EDM test show that the brass electrodes with RP that are manufactured perform well and the total time that is required to machine the EDM electrode using RP is 15.8% less than the time that is required for a CNC machining process. [ABSTRACT FROM AUTHOR]

It has been previously reported that electrical discharge machining (EDM) performance can be improved by tool electrode vibration. However, the mechanism of vibration-assisted EDM has not been clarified and the optimal vibration condition remains unknown due to the difficulty in direct process observation. In this study, direct observation of the EDM gap by using a high-speed video camera through a transparent workpiece electrode made of single-crystal 4H-SiC was attempted. It was found that tool vibration caused discharge dispersion and discharge frequency increase, and this tendency was more significant at higher amplitudes and higher frequencies. In addition, tool vibration-induced periodic discharge was observed, which prevented concentrated discharge and short-circuiting. Accordingly, the machining speed was improved and surface roughness was reduced. This study succeeded for the first time in observing the discharge behaviors in vibration-assisted EDM, thus revealed the effects of key parameters for process optimization. [ABSTRACT FROM AUTHOR]

Water-in-oil (W/O) nanoemulsion can be an alternative working fluid to kerosene in sinking electrical discharge machining (EDM). W/O nanoemulsion can improve the material removal rate, reduce the relative electrode wear rate, and alleviate the pollution of conventional sinking EDM using kerosene. However, the mechanism of sinking EDM using W/O nanoemulsion is not fully understood. In this study, a set of comparative experiments of single-pulse discharge is conducted in W/O nanoemulsion and kerosene to clarify the discharge mechanism of W/O nanoemulsion. The main machining parameters, which are crucial in actual sinking EDM, including pulse duration, peak current, and electrode polarity, are investigated. Precise geometries of the corresponding craters generated at the critical discharge gap are determined by the combination of optical instruments and 3D-rebuilt method. The effect of the working fluid flushing on the discharge machining is also analyzed. The results demonstrate that by the introduction of nanodroplets, the critical discharge gap is enlarged in W/O nanoemulsion. Compared with kerosene, W/O nanoemulsion has higher viscosity and density, which leads to stronger restrictions to the plasma channel and the motions of bubbles; therefore, larger volumes of melted materials and craters are formed in W/O nanoemulsion. This difference between W/O nanoemulsion and kerosene rises with the increasing discharge energy. Moreover, the restriction effect from working fluid is insignificant in the case of negative electrode polarity. [ABSTRACT FROM AUTHOR]

The modern industry which widely utilized sinking electrical discharge machining (EDM) with kerosene has many problems including low processing efficiency, unsafety, unfriendly environmental impact, and poor machined surface accompanying with recast layer. In this paper, a new water-in-oil (W/O) nanoemulsion dielectric is proposed to overcome these shortcomings of conventional sinking EDM. The machining performance and mechanism of sinking EDM using W/O nanoemulsion are investigated in both rough and finishing machining by comparing with kerosene. The main characteristic parameters for evaluating machining performance, including material removal rate (MRR) and relative electrode wear rate (REWR) in rough machining, and machined surface quality in finishing machining are studied. Compared with kerosene, using W/O nanoemulsion as a dielectric in sinking EDM, a nearly 34 times higher MRR and a relatively lower REWR are obtained in rough machining, and a better machined surface with no recast layer is attained in finishing machining. [ABSTRACT FROM AUTHOR]

Electrical discharge machining (EDM) is a non-conventional machining process, widely used in the modern industry. The stochastic nature of the process and the complexity of the occurring phenomena are the major difficulties in modeling of EDM. The current study presents a novel approach on EDM modeling, by coupling a heat transfer thermal analysis with deformed geometry feature. The deformation rate was calculated proportional to the spark erosion, leading to more accurate and realistic results. To validate the simulations results, a series of experiments were carried out on AISI O1 work-steel, with changing machining parameters the pulse current and the pulse-on time. The model validation criteria were the geometry of the formed craters, the average white layer thickness, and the heat-affected zone thickness. The simulation results were in agreement with experimental ones, suggesting that deformed geometry feature is important and suitable in modeling of EDM. [ABSTRACT FROM AUTHOR]

In the orbital mode of electrical discharge machining (EDM), an electrode with a complex profile causes deviation in the cavity profile from the design objective. In this paper, electrode compensation techniques according to the envelope theory are presented to eliminate deviation errors. The succession of orbits traced out a family of electrode curves based on kinematic geometry integrated with the motion path of tool bodies and constraints. The boundary of the family of electrode curves is referred to as the orbiting profile. The deviation error between the orbiting and objective profiles can be eliminated by using a compensation electrode in the orbiting process. Thus, the generated orbiting profile conforms to the objective profile. Experimental results of the tested example for the machining profile of the compensation electrode by using the orbital process revealed that profile deviation can be eliminated to ensure that the EDM profile closely conforms to the objective profile. This compensation method for orbiting EDM provided an exact process to engineers for easy control of the machining precision of EDM. [ABSTRACT FROM AUTHOR]

Application of external magnetic field in electrical discharge machining is one of the methods to increase this process capability and decrease its limitations. In the present study, a single discharge in magnetic field-assisted electrical discharge machining has simulated using finite element method in order to obtain the temperature distribution and generated crater dimensions on the workpiece surface. A new mathematical model for plasma channel radius was also developed and used at simulation stage. Regarding good agreement between recast layer thickness obtained by numerical and experimental methods with maximum error of 8.8%, the effects of applying external magnetic fields on plasma flushing efficiency and recast layer thickness were found numerically and experimentally. Also the influences of pulse current and pulse on-time on dimensions of generated craters at magnetic field-assisted EDM were studied numerically. The results showed the positive effects of application of external magnetic field in EDM process on increasing plasma flushing efficiency and decreasing recast layer thickness. [ABSTRACT FROM AUTHOR]

Abstract Electrical discharge machining is a significant non-traditional technique, widely used in the precise manufacturing field. However, the electrical discharge machining process possesses plenty of energy consumption and hazardous exhaust emissions. Since a sustainable machining technique, external magnetic field assisted, could dramatically develop sustainable machining performance of electrical discharge machining process, this paper presents a comparative study energy efficiency and environmental impact in magnetic field assisted electrical discharge machining and conventional electrical discharge machining. A novel thermo-physical model was proposed to calculate energy distribution under the single/continuous discharge, which was verified by a series of corresponding experiments. Then, based on simulation and experimental methods, a comparative study on the magnetic field assisted electrical discharge machining and conventional electrical discharge machining was conducted to analyze the discharge energy flowing and temperature distribution of workpiece, electrode tool and debris. Moreover, the effects of external magnetic field on the machining performance, environmental impacts and energy efficiency were presented. Eventually, it can be found out that the effect of magnetic field contributes to increasing energy utilization efficiency by 15.2%, material erosion efficiency by 22.6%, and material removal rate by 21.9%. To balance energy efficiency and surface roughness (Ra), the optimal parameter combination is obtained as below: magnetic field intensity: 0.2T, discharge current: 7–9A, and pulse duration: 300s. Highlights • Magnetic field assisted EDM improve energy efficiency and environmental impact. • A thermo-physical model is proposed to calculate energy distribution of MF-EDM process. • Sustainable machining performance of EDM and MF-EDM are comparatively investigated. • The optimal parameter is: magnetic field intensity: 0.2T, current: 7∼9A, and pulse duration: 300μs. [ABSTRACT FROM AUTHOR]

Micropencil grinding tools (MPGTs) are micromachining tools that use superabrasives like diamond and cubic boron nitride (cBN) grits to manufacture complex microstructures in a broad range of hard and brittle materials. MPGTs suffer from a rather low tool life, when compared to other more established microprocessing methods. It was documented that when used on hardened steel workpieces, MPGTs suffer from a large amount of adhesions, mostly located at the pivot point of the tool. These adhesions lead to the clogging of the abrasive layer and ultimately in tool failure. Another problem this machining process suffers from is the formation of substructures (smaller channels inside the microchannels). The pivot is usually less prone to abrasive wear, has higher protrusion, and is therefore responsible for the deepest substructures. These substructures can easily take up half the depth of cut, obstructing the function of machined microchannels--it is one of the major flaws of this micromachining process. A micro-electrical discharge machining method (μEDM) can solve these issues by manufacturing a cavity at the pivot of these tools. A novel method that uses measurement probes to position the substrate above the μEDM electrode is implemented and a parameter study to determine the cavity manufacturing parameters is conducted for substrates with diameters<40μm. The goal is to demonstrate the first ever complete and reliable manufacturing process for MPGTs with a cavity and to demonstrate the advantages they provide in a machining process when compared to regular MPGTs. [ABSTRACT FROM AUTHOR]

Electrical discharge machining (EDM) is extensively used for machining difficult-to-machine materials and complicated shapes. Its performance in terms of material removal rate and surface roughness is usually analyzed using the process parameters such as setting voltage, setting current, pulse on time, and duty factor. It is well known that interelectrode gap condition controls the EDM performance, and it is difficult to observe the gap phenomena directly. Literature reveals that the combined influence of pulse types and their individual contributions on material removal rate and surface roughness has been ignored. In the present work, rough and finish EDM conditions are identified from a large set of 125 experiments carried out on hardened D3 die steel. From the voltage and current pulse trains in each regime, pulse characteristics and five different pulse types are assessed by a unique thresholding approach. Based on the pulse details, two new parameters such as energy expended (E) at the electrode gap over a second and a performance factor (PF) giving ratio of energy associated with the sparks to total energy expended have been proposed. It is found that a higher PF of 0.757 at a relatively lower expended energy of 113.7 J leads to a favorable condition in rough machining. A relatively lower E of 29.7 J and a higher PF of 1.00 are favorable for finish machining. Cross-sectional images of the ED machined workpieces are also included as evidences. The proposed thresholding methodology has a potential for online monitoring, analysis, and control of EDM process. [ABSTRACT FROM AUTHOR]

Abstract In micro-electrical discharge machining (micro-EDM), the minimum machinable size is determined by the material removal per pulse discharge. In this study, two types of single-crystal silicon tool electrodes with high electrical resistivity were used to fabricate the micro-rod by minimizing the material removal per pulse discharge, and to reduce the machinable size for micro-EDM. The EDM characteristics of micro-rods using silicon tool electrodes with high electrical resistivity were investigated. Based on the experimental results, it is found that the peak discharge current decreases with an increase in the electrical resistivity of the tool electrode. Consequently, the average diameter of discharge craters generated on the micro-rods is reduced to approximately 0.4 μm. The silicon tool electrode has also disadvantage of their higher tool wear ratio compared with that of copper, which is probably due to the brittleness of the silicon. Moreover, the material removal rate is significantly lower for the silicon tool electrodes compared with that for the copper tool electrode. Because the average diameter of the discharge craters generated by the silicon tool electrodes is small, an attempt is made in this study to fabricate a cemented tungsten carbide micro-rod with a diameter less than 1 μm using the silicon tool electrode with an electrical resistivity of 1.2 × 10−3 Ω m. The result is indeed promising since the diameter of the micro-rod is 0.8 μm, indicating that it is possible to fabricate micro-rods with a diameter within the sub-micrometer range by only using silicon tool electrode with high electrical resistivity in micro-EDM. Highlights • The peak discharge current decreases with an increase in the resistivity of the tool electrodes. • The diameter of discharge craters decreases by increasing the resistivity of the tool electrodes. • The tool wear ratio is higher for the silicon tool electrodes compared with that for copper. • The material removal rate is lower for the silicon tool electrodes compared with that for the copper tool electrode. • A cemented tungsten carbide micro-rod with a diameter of 0.8 μm is fabricated. [ABSTRACT FROM AUTHOR]

Ni-Al2O3 functionally graded materials (FGMs) have become important for high-temperature applications due to a continuous change in graded layers. However, the manufacturing process of Ni-Al2O3 FGMs with the traditional pulse power is a long process because the pulse power cannot real-timely adjust machining parameters to adapt the change of graded layers. This paper designed a real-time monitoring module and a parameter adjustment module, which can identify different graded layers and actively adjust machining parameters to adapt the change of graded layers. By means of the monitoring module, four major discharge states, normal, arc, insufficiency, and long pulse discharge state have been discriminated real-timely. The 70% Ni/30%Al2O3 layer and 30% Ni/70%Al2O3 layer have been distinguished based on the quantitative analysis of insufficiency and long pulse discharge waveforms. Multi-layers of Ni-Al2O3 FGMs are machined to validate the machining performance of the parameter adjustment module. Experiment results demonstrate that by adjusting the open voltage, the machining efficiency of 30% Ni/70%Al2O3 layer has been increased by six times, resulting in more time-efficient EDM process of Ni-Al2O3 FGMs. [ABSTRACT FROM AUTHOR]

In this paper, an inexpensive auxiliary tool vibration device is described that improves the efficiency of deep groove electrical discharge machining (EDM). Titanium alloy samples (Ti-6Al-4V) were machined using two different methods: unassisted normal EDM and vibration-assisted EDM, using copper, copper-tungsten, and graphite tool electrode materials. The vibration-assisted EDM machining was done at 40, 90, and 140 Hz, and the material removal rate, tool electrode wear rate, and surface roughness of the specimens were compared. Experimental results revealed that the material removal rate with vibration-assisted EDM was better than that obtained using unassisted EDM with copper and copper-tungsten electrodes. In this study, the vibration frequency was found to have an optimum value of 90 Hz with respect to surface roughness. It was found that the machining time for a groove 10 mm deep with vibration-assisted EDM was reduced by 200% compared to unassisted EDM. This new vibration device can help in the development of a more efficient deep groove EDM. [ABSTRACT FROM AUTHOR]

• Multi-physics coupling model considering practical boundary conditions was developed. • The effect of difficult forces acting on melt pool were analyzed. • The role of evaporation recoil pressure on material removal was revealed. • Melt pool dynamics and material removal were directly observed and analyzed under practical conditions. The melt pool dynamics and material removal mechanism in electrical discharge machining (EDM) is not clear yet. In this study, a thermo-hydraulic coupling simulation model considering practical boundary conditions was proposed to investigate the melt pool evolution and material removal on the anode in EDM, with the simulated results directly verified by the high-speed observation of the discharge process. Discharge currents of 5–15 A, a discharge duration of 10 µs, and workpieces of zinc and steel were used in the model, with the forces acting on the melt pool comprehensively integrated and their effects on the melt pool dynamics and material removal analyzed. The simulation results show that on the anode the evaporation recoil pressure is one of the dominant factors that drive the melt flow and cause the molten material removal. The increase of discharge current results in larger evaporation recoil pressure, and thus larger volume of the molten material is removed. Under the effect of evaporation, obvious fluctuation of the melt pool will occur. Meanwhile, the evaporation recoil pressure oscillates with the melt pool fluctuation, which may induce a wave-like motion of the molten material and promote the generation of debris particles. Novel high-speed observation methods were proposed to observe the melt pool evolution and the material removal, with the observed melt pool behavior consistent with the simulated results. The observation also shows that the intermittent removal of the molten material occurs in the case of long discharge duration, which is considered to be caused by the intermittent increase of the evaporation recoil pressure during the melt pool fluctuation. [Display omitted] [ABSTRACT FROM AUTHOR]

Electrical discharge machining (EDM) has been recommended as the most effective way to produce an integral shrouded blisk, whereas its low machining efficiency cannot meet the batch production requirements of this component. An electrode feeding method with perturbations in the EDM process of the integral shrouded blisk is proposed, in which extra perturbations are periodically added on the original feeding path. Those perturbations are perpendicular to the original feeding path and are determined by two parameters: separation distance and perturbation factor. The optimal perturbation parameters for blisk EDM machining are experimented to be a separation distance of 2.5 mm combined with a perturbation factor of 30%. Compared with the electrode feeding method without perturbations, that with perturbations had a better discharge status. A machining time reduction of 18.45% was achieved in the EDM process of a real integral shrouded blisk by using the electrode feeding method with perturbations. [ABSTRACT FROM AUTHOR]

This paper presents a hybrid electrochemical discharge drilling method in which a metal tube is used as cathode tool and workpiece is used as anode. Liquid with weak conductivity flows at high speed between the metal tube and workpiece. Electrical discharge takes place mainly at the frontal gap, and electrochemical process takes place at both the frontal gap and side gap. The recast layer generated by electrical discharge at the side gap can be removed electrochemically. The machining phenomenon at the gap was observed through a designed transparent clamping fixture, voltage and current waveforms during machining were recorded, and the machining products and removal effect of recast layer were analyzed. The cross section of the hole and machining surface were analyzed, and the tool wear and machining efficiency were compared with those of other processes. Finally, the 4-mm-deep hole of 0.5-mm diameter can be produced with low tool wear and almost no recast layer. [ABSTRACT FROM AUTHOR]

Surface modifications of biomaterials play a vital role in matching the complexities of the biological system and improving the performance of bioimplants. Suitably customised surface modifications can substantially enhance the relation of material towards biocompatibility, bondability and host cells associations. In addition, materials surface engineering accelerates the progression and configuration of next-generation biomaterials and restorative gadgets. This review article dedicates to the surface modification techniques of several essential metallic biomaterials, viz. stainless steel, magnesium, titanium and chromium-cobalt. It presents the unique novel futuristic method of surface modification via electrical discharge machining (EDM) process which still awaits to prove its potential in the biomedical domain. Previously established research work on this nonconventional machining process elucidates that an adequate surface integrity can be achieved by control of crucial EDM process parameters such as pulse on, pulse off, current, polarity, dielectric medium and tool electrodes. Therefore, there is ample scope for the EDM process in examining the issues related to the synthesis and precise shaping of the bioimplants. [ABSTRACT FROM AUTHOR]

Electro discharge machining (EDM) process need to be optimized when a new material invented or even if some process variables changed. This process has many variables and it is always difficult to get the optimum set of variables by chance. Therefore, an optimization process need to be conducted considering different combinations of machining parameters as well as other variables even if the process were optimized for a certain set of variables. Optimization of the EDM process for machining stainless steel 304 (SS304) (ASTM A240) was studied in this paper. Signal-to-noise ratio (S/N) was calculated for each performance measures, and multi response performance index (MRPI) was generated using fuzzy logic inference system. Optimal machining parameters for machining SS304 materials were identified, namely current 10, pulse on time 60 µs, and pulse off time 35 µs. Analyses of variances (ANOVA) method was used as well to see which machining parameter has significant effect on the performance measures. The result of ANOVA indicates that pulse off time and current are the most significant machining parameters in affecting the performance measures, with the pulse off time being the most significant parameter. [ABSTRACT FROM AUTHOR]